The present invention relates to an FM receiver, and also to FM communication systems including such a receiver. The invention is particularly adaptable for miniaturization since it requires very little power, thereby making it eminently suitable for use as an earplug or earphone in a hearing aid, hands-free receiver, or the like.
In FM communication, the frequency of a carrier of fixed amplitude is varied above and below the normal carrier frequency in accordance with the signal to be transmitted. The FM receiver must therefore also include an FM discriminator producing an output voltage varying with the frequency of the received FM signal. This output voltage is used as the audio signal for producing the sounds in an audio system.
The FM receiver also includes a limiter for limiting the amplitude of the received FM signal. In the conventional FM receiver, the limiter is usually an amplifier which is driven to saturation. Such conventional systems therefore consume considerable energy, which requires the use of larger batteries, or the more frequent replacement of the batteries, neither of which is desirable when the receiver is embodied in an earplug or earphone such as used in hearing aids, hands-free communication, or the like.